In his nearly two years in office, President Obama has relied on a very small clique of advisers that serves as his most trusted sounding board on politics and policy.

Members of his staff describe Obama as wary of outsiders and reluctant to widen his inner circle. As one of his advisers bluntly put it, the president "doesn't like new people."

Like it or not, he will soon be surrounded by them as an expected staff shuffle will deprive Obama of two of his closest aides and an influx of replacements will take their places within the West Wing.

Obama will soon lose other top advisers. His chief economic adviser, Lawrence H. Summers, announced that he will return to Harvard, where he is a professor; Deputy Chief of Staff Jim Messina is expected to join Axelrod in Chicago; and national security adviser James L. Jones is said to want out by the end of the year.

Some former aides and allies of the president expressed hope that Obama will take advantage of the departures - which are common at the two-year point in any presidency - to bring in outsiders who will challenge the president's current team.

"They miscalculated where people were out in the country on jobs, on spending, on the deficit, on debt," said a longtime Democratic strategist who works with the White House on a variety of issues. "They have not been able to get ahead of any of it. And it's all about the insularity. Otherwise how do you explain how a group who came in with more goodwill in decades squandered it?" The strategist asked not to be identified in order to speak freely about the president and his staff.

This is not an uncommon view among Democratic political professionals, many of whom share the goals of the White House but have grown frustrated with a staff they see as unapproachable and set in their ways.

But Obama might not look too far beyond the walls of the White House in his search for new advisers. In the pervasive but often unreliable Washington guessing game, the names most often heard are already familiar to the president: Tom Donilon, Obama's deputy national security adviser, is thought to be a leading contender either for Emanuel's job or for Jones's post. Donilon and Obama became close during the 2008 campaign, when he was in charge of prepping the candidate for debates.

Senior adviser Pete Rouse is another possible choice to replace Emanuel. He served as Obama's chief of staff in the Senate. Other possible candidates include Bob Bauer, the White House counsel, who was the president's personal attorney before he joined the administration last year; Phil Schiliro, who runs Obama's congressional liaison office; and former Senate majority leaderTom Daschle, a close Obama ally.

Recent White House hires reflect the president's desire to surround himself with people he knows well. Elizabeth Warren, recently tapped as the government's first consumer protection adviser, is someone Obama describes as a "dear friend." Austan Goolsbee, brought in as the new chairman of the Council of Economic Advisers, has been in the Obama orbit much longer than the woman he replaced, Christina Romer.

White House officials resist the notion that they are an out-of-touch palace guard. They say Obama is presented with a wide range of views from people inside and outside of the administration. And, they point out, the inner circle does not always get its way. Emanuel and Biden, for example, were on the losing side of debates over how to approach health-care reform (Emanuel argued against taking it up so early in Obama's first term) and the war in Afghanistan (both were against the troop surge).

"I believe the circle of people this president talks to on a daily basis is more new to him than not," Gibbs said.

But in moments of reflection, and at the beginning and end of each day, Obama turns to his five trusted advisers to bounce around ideas and solicit feedback. When the president was trying to decide whether to fire Gen. Stanley McChrystal after an embarrassing article appeared in Rolling Stone, he made numerous calls to officials on the outside. When he ultimately made his decision, a small group of insiders - in this case, Gibbs, Emanuel, Axelrod, Biden and the National Security Council's chief of staff, Denis McDonough - was the first to know. Generals at the Pentagon found out the next day.

"This is the way Kennedy worked," said Democratic strategist Peter Fenn, whose father, Dan Fenn, ran the Kennedy Library after working in the Kennedy administration. "He had his group - Ken O'Donnell, Larry O'Brien, Ted Sorensen, Ralph Dungan, Lee White - a very small group of guys that had been with him a long time, that worked with him closely and whose judgment he trusted."

Alone in Obama's administration, Obama's five closest advisers have the freedom to walk into the Oval Office unannounced and to attend virtually any meeting, allowing them more time with the president and a greater ability to sway his thinking. They assume multiple, sometimes ill-defined roles, with their jobs crossing into multiple lanes, often across one another's areas of expertise.

Although there are internal tensions within the group, they have been together in one way or another for years; Jarrett, Axelrod and Gibbs worked with Obama long before the 2008 campaign, while Emanuel knew him from Chicago, and Biden from the Senate.

One presidential ritual illustrates his special relationship with these aides. Each evening, before Obama heads upstairs to the White House residence, an aide hands him a briefing book stuffed with reports, memos and statistics on the day's business from all corners of his administration. The next morning, Obama hands back "the book," margins scribbled with demands for more information, meetings or action on its contents. Aside from the president, only Axelrod, Gibbs, Jarrett, Emanuel and Biden receive copies of both the outgoing and incoming versions of the book.

Emanuel, Obama's chief of staff, is the first to see him in the morning and the last to see him before he retires for the night. The two hold an end-of-day discussion on what happened that day and what is coming up. Emanuel then brings in the others at the staff meeting he holds each morning at 7:30 a.m.

Emanuel's successor and the other new hires will probably have to learn to fit into Obama's highly regimented way of doing business.

"In this White House, you know who the president has met with and the last person he's going to meet with," a senior adviser said. "And that's what works for this president. It's not going to change."